Over on YouTube Leif 'sm5bsz' has uploaded a video that does a lab comparison of various SDRs on the market now including the new Airspy HF+. Leif is known for providing excellent lab based technical reviews of various SDR products on his YouTube channel.

The first video compares the Airspy HF+ with the Perseus SDR. The Airspy HF+ is a new high performance yet low cost ($199 USD) HF/VHF specialty SDR. The Perseus is an older high performance direct sampling HF only SDR, although it comes at the high price of about $1000 USD.

In his tests Leif tests both units at 14 MHz and finds that the HF+ has about 15 dB better sensitivity compared to the Perseus (NF = 7dB vs 22dB). On the other hand the Perseus has about 23 dB better dynamic range compared to the HF+ (Dynamic Range = 127 dBc/Hz vs 150 dBc/Hz), although he notes that a blocking transmitter needs to have a very clean signal to be able to notice this difference which would be unlikely from Amateur transmitters.

In the RX4 video Leif compares each SDR on dynamic range at 7 MHz. If you want to skip the testing parts, then the discussion of the results in the RX4 tests start at 1:03:00. A screenshot of the results is also shown below. The SDRs are ranked based on their average results over multiple measurements at different times which is shown in the last column. A lower value is better, and the value represents how much attenuation needed to be added to prevent the SDR from overloading and causing interference in his setup.

Dynamic Range Test Rankings

rx4compare

In the RX5 video the results start at 54:20:00. In this video he compares the SDRs with real signals coming in from his antenna at 7 MHz. He tests with the antenna signal wide open, with a 4.5 MHz LPF (to test out of band blocking performance), and with a bandpass filter at 7 MHz. Again lower values are better and the values indicate the amount of attenuation required to prevent overload. The Perseus is used as the reference benchmark. He also tests reciprocal mixing later in the video.

8 comments

A classic general coverage receiver and a SDR are two different things and can not be compared. You don’t compare email with classic letter service, are you? We should not exaggerate some things to something magical. SDR is powerful.

About pricing… I you dismantle your DSL- or cable modem you will realize, that for a few bucks you get 10-times the technology of a Perseus or whatever..

The final question is : which one offers the best price / performance ratio ? (not considering frequency coverage). Is Perseus 4x better compared HF+ ou 7x better compared to SDRplay assuming it costs respectively 4 and 7 times as much as these SDRs ?

The answer depends on the application. DX listening in quiet rural area is one application, casual listening in a noisy suburb is completely different.
Based on Leif’s comparison, you chose the best tool for your job.

In the third paragraph, the notes about the Perseus versus the Airspy HF+ are not about dynamic range. It has to do with local oscillator phase noise. It does have an effect on close-in dynamic range, but you need very strong signals adjacent to very weak signals to be able to measure much difference.

And by the way, 150 dBc/Hz is in the excellent/unbelievable category for a general coverage receiver. Even 127 dBc/Hz is nothing to sneer at, particularly when discussing a receiver at this price.

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What is RTL-SDR

The RTL-SDR is an ultra cheap software defined radio based on DVB-T TV tuners with RTL2832U chips. The RTL-SDR can be used as a wide band radio scanner. It may interest ham radio enthusiasts, hardware hackers, tinkerers and anyone interested in RF.